This specification relates to image search using query images.
Search engines aim to identify resources (e.g., images, audio, video, web pages, text, or documents) that are relevant to a user's needs and to present information about the resources in a manner that is most useful to the user. Search engines return a set of search results in response to a user submitted query. For example, in response to an image search text query (i.e., a query to identify image resources), the search engine returns a set of search results identifying image resources responsive to the query (e.g., as a group of thumbnail representations of the image resources). Typically, queries are text queries, e.g., queries having one or more search terms or query phrases.